Effect of Processing on Mechanical Properties of Platelet-Reinforced Mullite Composites

SiC- and Al₂O₃-platelet-reinforced mullite-matrix composites were fabricated by both conventional powder processing and a pressure filtration route with constant filtration rate. Consolidation during the pressure filtration experiment was monitored as a function of time with respect to actual pressing stages. The packing density of green bodies was strongly affected by the different processing methods. Either fracture toughness (3.2 MPa · m^1/2) or bending strength (344 MPa) increased, depending on surface conditioning of the SiC platelets. Pressure filtration was shown to decrease processing flaws in the platelet-reinforced bodies leading to substantial improvement of the mechanical properties.